Nobody uses the “rythm method” anymore. NFP institutes what is called the Sympto-thermal Method. And the Church teaches that it should not be used selfishly. Do some Catholics do that? Sure. But it’s wrong.
My wife and I used it in order to achieve pregnancy. It worked. We have two beautiful daughters. But now being past the age for having kids we now use it to avoid pregnancy. All within the boundaries set by the Curch.
Clearly I spoke with a lack of precision, but that doesn’t change my point.
Yes, set by “The C[h]urch” i.e. a bunch of people who thought God gave them a license to treat His glory like Play-Doh!